Specifications

Centronics Printer Interface
The printer interface is a bidirectional parallel data port that fully
supports the parallel Centronics type printer. This parallel port may be
used either for basic I/O or for a printer. It consists of eight I/O lines
for data, four open-collector I/O lines for control, and five input lines
for status. These signal groups are available at the Data Port, Control
Port, and Status Port registers, respectively. The open-collector lines
have internal 2.5 kΩ pullups to +5 V.
Figure 9-1 is a block diagram of the printer interface, which resides in
the 16C452 ASIC. It also contains the two serial ports on board,
further described in Chapter 8.
Buffer
Jumper
CPU
ZT 8808A/8809A
Functions
LPT1
INT
Centronics
Printer
Port
(LPT1)
PD0-7
INIT
STROBE
AFD
SLIN
ERROR
SLCT
BUSY
PE
ACK
LPTOE
2.2K
+
470
Figure 9–1. Printer Interface Block Diagram.
9-2